Implant fixation device

ABSTRACT

Disclosed is an orthopedic implant that includes an anchor, a bore, and a compressible and expandable mesh. The anchor is configured to secure the implant at an implantation site and defines a longitudinal axis. The bore is defined by the anchor and extends along the longitudinal axis. The compressible and expandable mesh is aligned along the longitudinal axis and defines a plurality of openings. The mesh is configured to compress along the longitudinal axis and expand from the longitudinal axis to engage surrounding bone or tissue at the implantation site to secure the implant at the implantation site.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/761,345 filed on Feb. 7, 2013, now U.S. Pat. No. 8,968,415, whichclaims the benefit of U.S. Provisional Application No. 61/595,832, filedon Feb. 7, 2012. The entire disclosure of the above application isincorporated herein by reference.

FIELD

The present disclosure relates to orthopedic implant fixation devices,including expandable fixation devices.

BACKGROUND

This section provides background information related to the presentdisclosure, which is not necessarily prior art.

To secure orthopedic implants to bone, various fixation devices areoften used, such as pins and screws. While current fixation devices aresuitable for their intended use, they are subject to improvement.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

The present teachings provide for an orthopedic implant that includes ananchor, a bore, and a compressible and expandable mesh. The anchor isconfigured to secure the implant at an implantation site and defines alongitudinal axis. The bore is defined by the anchor and extends alongthe longitudinal axis. The compressible and expandable mesh is alignedalong the longitudinal axis and defines a plurality of openings. Themesh is configured to compress along the longitudinal axis and expandfrom the longitudinal axis to engage surrounding bone or tissue at theimplantation site to secure the implant at the implantation site.

The present teachings further provide for an orthopedic implant thatincludes a hemispherical bone engaging outer surface, a concavearticulation surface, and a retention component. The concavearticulation surface is opposite to the bone engaging surface. An axisof the implant extends through an axial center of the concavearticulation surface. The retention component is at an exterior of theimplant and is configured to compress along the axis and expand from theaxis to engage surrounding bone or tissue at an implantation site tosecure the implant at the implantation site.

The present teachings still further provide for an orthopedic implantincluding a base, an anchor, a connector, and a resiliently compressiblemesh portion. The base includes a first side and a second side that isopposite to the first side. The anchor extends from the first side ofthe base. The connector extends from the second side of the base. Theresiliently compressible mesh component is included in the base portionor attached to the connector. The mesh component is configured to retainthe implant at an implantation site.

The present teachings also provide for an orthopedic implant thatincludes a cup component and a retention component. The cup componentincludes a hemispherical bone engaging outer surface, a concavearticulation surface, and a plurality of concave biasing surfaces. Theconcave articulation surface is opposite to the bone engaging surface.The axis of the cup component extends through an axial center of theconcave articulation surface. The plurality of concave biasing surfacesare spaced apart about an equator of the hemispherical bone engagingsurface. The retention component includes a retention ring and aplurality of retention barbs that extend from the retention ring and arespaced apart about the retention ring. Upon compression of the retentioncomponent onto the cup component such that the retention barbs contactthe biasing surfaces, the retention barbs are forced outward from theaxis to engage surrounding bone or tissue at an implantation site tosecure the implant at the implantation site.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is a side view of an implant according to the present teachings;

FIG. 1A is a close-up sectional view of interaction between a fastenerand a bore of the implant of FIG. 1;

FIG. 2 is a perspective view of the implant of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1;

FIG. 4 is a perspective view of the implant of FIG. 1 in cooperationwith a driver;

FIG. 5 is a side-view of the implant of FIG. 1 in a compressed position;

FIG. 6 is a perspective view of the implant of FIG. 1 in cooperationwith a compression tool;

FIG. 7 illustrates the implant of FIG. 1 implanted in a femur bone;

FIG. 8 is an exploded view of another implant according to the presentteachings;

FIG. 8A is a cross-sectional view taken along line 8A-8A of FIG. 8;

FIG. 9 is a side view of the implant of FIG. 8;

FIG. 9A is a close-up sectional view of interaction between a fastenerand a receptacle of the implant of FIG. 9;

FIG. 10 is a side view of the implant of FIG. 9 in a compressedposition;

FIG. 11 is a side view of the implant of FIG. 9 moved to a compressedposition with a compression tool;

FIG. 12 illustrates the implant of FIG. 9 implanted in a femur;

FIG. 13 is an exploded view of another implant according to the presentteachings;

FIG. 14 is a side view of the implant of FIG. 13;

FIG. 15 is a cross-sectional view taken along line 15-15 of FIG. 15;

FIG. 16 is a side view of the implant of FIG. 13 in a compressedposition;

FIG. 17 is a side view of the implant of FIG. 13 moved to a compressedposition with a compression tool;

FIG. 18 illustrates the implant of FIG. 13 implanted in a femur;

FIGS. 18A-18C illustrate implantation of the implant of FIG. 13 in thefemur;

FIG. 19 is a disassembled view of another implant according to thepresent teachings;

FIG. 20 is a cross-sectional view taken along line 20-20 of FIG. 19;

FIG. 21 is a side view of a sleeve compression tool;

FIG. 22 is a side view of the implant of FIG. 19 in an uncompressedposition in a femur bone;

FIG. 23 is a side view of the implant of FIG. 19 in a compressedposition and anchored in a femur;

FIG. 24 is a side view of the implant of FIG. 19 anchored in a femurwith a distal femoral implant secured thereto;

FIG. 25 is a side view of the implant of FIG. 19 anchored in a femurwith a distal femoral implant secured thereto, the distal femoralimplant including a compressible mesh portion;

FIG. 26 is a perspective view of another implant according to thepresent teachings;

FIG. 27A is a perspective view of an additional implant according to thepresent teachings in an uncompressed position, the implant configured asan acetabular cup implant;

FIG. 27B is a perspective view of the implant of FIG. 27A, the implantin a compressed position;

FIG. 28 is a perspective view of the implant of FIG. 27A and a cupcompressor;

FIG. 29 illustrates the implant of FIG. 27A implanted in a pelvis;

FIG. 30A is a perspective view of another implant according to thepresent teachings;

FIG. 30B is a perspective view of a further implant of the presentteachings;

FIG. 31 is an exploded view of an another implant according to thepresent teachings;

FIG. 32 is another view of the implant of FIG. 31;

FIG. 33 is a sectional view illustrating assembly of the implant of FIG.31;

FIG. 34 is a sectional view illustrating the implant of FIG. 31assembled;

FIG. 35 illustrates the implant of FIG. 31 implanted in a pelvis;

FIG. 36 is a side view of another implant according to the presentteachings; and

FIG. 37 is a top view of the implant of FIG. 36.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With initial reference to FIGS. 1-5, an orthopedic implant according tothe present teachings is illustrated at reference numeral 10. Theimplant 10 generally includes a base 12, a connector or coupler 14, andan anchor or stem 16. The base 12 is between the connector 14 and thestem 16.

The base 12 generally includes a first surface 18, a second surface 20that is opposite to the first surface 18, and a side surface 22 that isbetween the first surface 18 and the second surface 20. The base 12defines an aperture 24 at the first surface 18. The aperture 24 isaligned with, and provides access to, a counterbore 26 defined by thebase 12. The aperture 24 and the counterbore 26 are generally at anaxial center of the base 12, which is aligned with a longitudinal axis Aof the stem. As illustrated in FIG. 2 for example, the side surface 22generally defines an oval shape and the second surface 20 generallydefines a concave shape. The base 12 can define any other suitable shapeto correspond to an opposing surface that contacts or is near theimplant 10 when implanted.

The connector 14 extends from the first surface 18 of the base 12. Asillustrated, the connector 14 is offset from the center of the firstsurface 18 and the longitudinal axis A. The connector 14 includes a baseend 28 at the first surface 18 and a tip end 30 that is opposite to thebase end 28. A sidewall 32 extends between the base end 28 and the tipend 30. The sidewall 32 is tapered from the base end 28 to the tip end30 such that the sidewall 32 has a smaller diameter at the tip end 30than the base end 28, thereby providing the connector 14 with a maleMorse taper surface. The connector 14 can be integral with the base 12or mounted to the base 12 in any suitable manner, such as with a weld.The connector 14 can be any suitable connector for connecting anotherimplant component to the connector 14, such as a femoral head 34 (FIG.7). The connector 14 may also be aligned with the longitudinal axis A orpositioned at any other suitable location of the first surface 18.

The stem 16 generally includes a base end 36 at the second surface 20 ofthe base 12 and a tip end 38 that is opposite to the base end 36. Acylindrical sidewall 40 extends between the base end 36 and the tip end38. The base end 36 of the stem 16 can be integral with the base 12 ormounted to the base 12 in any suitable manner, such as with a weld. Thestem 16 defines a bore 42 that extends along the longitudinal axis Afrom the counterbore 26 to the tip end 38. The bore 42 is generallycylindrical, as illustrated in FIG. 3 for example.

The stem 16 further includes a compressible mesh portion 44, which isbetween a first stem portion 46 and a second stem portion 48. The firststem portion 46 is between the base end 36 and the compressible meshportion 44. The second stem portion 48 is between the compressible meshportion 44 and the tip end 38. The first stem portion 46 and the secondstem portion 48 are generally non-compressible. As in the illustratedexample, the compressible mesh portion 44 extends from a point abouthalf-way between the base end 36 and the tip end 38 to a point aboutthree-quarters between the base end 36 and the tip end 38. However, themesh portion 44 can be at any suitable position between the base end 36and the tip end 38 and be of any suitable length.

The compressible mesh portion 44 includes a first end 50 that abuts thefirst stem portion 46 and a second end 52 that abuts the second stemportion 48. The first end 50 of the mesh portion 44 can be secured tothe first stem portion 46 and the second end 52 can be secured to thesecond stem portion 48 in any suitable manner, such as with a weld. Thefirst stem portion 46, the second stem portion 48, and compressible meshportion 44 can also be unitary or monolithic, and thus formed from asingle metallic portion, as further described herein.

At the compressible mesh portion 44, the sidewall 40 defines a pluralityof openings 54. At the first stem portion 46 and the second stem portion48 the sidewall 40 is generally solid. The openings 54 can be of anysuitable shape and size to permit compression of the mesh portion 44along the longitudinal axis A and expansion of the mesh portion 44 awayfrom the longitudinal axis A in a direction generally perpendicular tothe longitudinal axis A (as further described herein and illustrated inFIG. 5). For example, the openings 54 can be in the form of a latticestructure with generally uniform and adjacent diamond-shaped openings ofany suitable size, such as from about 0.25 mm to about 5.0 mm, such asabout 1.0 mm. The openings 54 can also be generally spaced apart slotsextending generally parallel to the longitudinal axis A and spaced apartat any suitable distance, such as from about 0.10 mm to about 1.0 mm,such as about 0.5 mm, and can be of any suitable size, such as fromabout 0.25 mm to about 5.0 mm, such as about 1.0 mm or about 2.0 mm.

The mesh portion 44 can also define openings 54 of any other suitablesize and shape, such as circular, hexagonal, octagonal, parallelogram,or rhombus shaped openings. The shape can be selected depending on thedegree of retention force or grip desired between the mesh portion 44and, for example, surrounding bone. For example, upon compression of themesh portion 44, diamond shaped openings will have sharper edges to moresecurely engage surrounding bone as compared to, for example, circularopenings. Hexagonal and octagonal shaped openings will often providegreater retention force when compressed to engage bone than circularopenings, but less than diamond shaped openings.

The openings 54 defined by the mesh portion 44 can be formed in anysuitable manner using any suitable manufacturing device and/ortechnique, such as wire electrical discharge machining, laser cutting,furnace brazing, fusion bonding, EOS laser sintering, and rapid metalprototyping. For example, the openings 54 can be formed using wireelectrical discharge machining to cut completely through a wall of thestem 16 to define the openings 54 therein. Further or alternatively,lattice material defining the openings 54 can be connected, such as bywelding, between the first stem portion 46 and the second stem portion48. The compressible mesh portion 44 can include any suitable material,such as a suitable biocompatible metal or polymer.

At the second stem portion 48, the bore 42 includes a plurality ofinternal threads 56. The threads 56 can extend from the tip end 38 tonearly the compressible mesh portion 44.

A fastener 60 is seated in the bore 42. The fastener 60 includes a head62 and a shaft 66, which includes external fastener threads 68 at adistal end 70. In the uncompressed position of FIGS. 1, 1A, 2, and 4,the shaft 66 is positioned such that the anchor head 62 is seated withinthe counterbore 26, the shaft 66 extends through a majority of the stem16, and the first few fastener threads 68 at the distal end 70 engagethe threads 56 of the bore 42 that are closest to the mesh portion 44.The head 62 includes a coupler 72 configured to mate with a suitabledevice for rotating the fastener 60, such as a driver 80.

As illustrated in FIGS. 4 and 5 for example, the compressible meshportion 44 can be compressed by rotating the fastener 60 with the driver80. Rotation of the fastener 60 causes the fastener 60 to cooperate withadditional threads 56 of the bore 42. Because the fastener 60 isrestricted from moving along the longitudinal axis A due to cooperationbetween the head 62 and the counterbore 26, the tip end 38 and thesecond stem portion 48 are drawn or driven toward the base 12 tocompress the mesh portion 44 between the first stem portion 46 and thesecond stem portion 48, each of which are generally non-compressible. Inaddition to being compressed, the mesh portion 44 expands outward fromthe longitudinal axis A (FIG. 5).

With reference to FIG. 6, the implant 10 can be compressed with acompression tool 90 if the fastener 60 is not included. The compressiontool 90 generally includes a handle 92, and a shaft 94 including adistal end 96. A plurality of tool threads 98 are at the distal end 96.A flange 99 is positioned along the shaft 94 such that the flange 99sits in the counterbore 26 of the implant 10 when the shaft 94 isinserted in the bore 42 of the implant 10, and the first few toolthreads 98 closest to the distal end 96 cooperate with the bore threads56 that are closest to the compressible mesh portion 44. To compress themesh portion 44 and force the mesh portion 44 to expand from thelongitudinal axis A, the compression tool 90 is rotated such that thetool threads 98 engage additional threads 56 of the bore 42, therebydrawing the second stem portion 48 toward the first stem portion 46 andcompressing the mesh portion 44 therebetween.

With reference to FIG. 7 the implant 10 including the fastener 60 isimplanted in a femur 102 to anchor the prosthetic femoral head 34. Theimplant 10 permits preservation of substantially all of femoral neck 104and can be secured in the femur 102 without the need for other fasteningmechanisms, such as transverse pins inserted through the neck 104 orbone cement. To implant the implant 10 in the femur 102, the naturalhead is resected and the femur 102 is milled or reamed through the neck104. The stem 16 is inserted through the neck 104 such that the secondsurface 20 of the base 12 is seated on an anterior surface 106 of theneck 104.

To secure the implant 10 in the neck 104, the fastener 60 is rotatedwith the driver 80 to compress and expand the compressible mesh portion44 as described above. The compressible mesh portion 44 expands from thelongitudinal axis A to engage and extend into sidewalls 108 of themilled portion of the neck 104. While cooperation between the meshportion 44 and the sidewalls 108 is typically sufficient to retain theimplant in the femur 102, bone cement or other adhesives may be added toaugment fixation. The femoral head 34 includes a female Morse taper 109,which cooperates with the male Morse taper connector 14 to secure thehead 34 to the implant 10. If the implant 10 does not include thefastener 60, it is implanted in the same manner and the compression tool90 can be used to compress and expand the mesh portion 44 as describedherein. While the implant 10 is illustrated as a femoral implant, thecompressible mesh portion 44 can be included in an anchoring stem of anyother suitable type of implant to facilitate fixation of the implant tobone or tissue.

With additional reference to FIGS. 8-10, another implant according tothe present teachings is illustrated at reference numeral 110. Theimplant 110 generally includes a base 112, a connector 114 mounted to afirst surface 116 of the base 112, and an anchor or stem 118 mounted toa second surface 120 of the base 112. The first surface 116 is oppositeto the second surface 120 and a side surface 122 extends therebetween.The connector 114 is substantially similar to the connector 14 of theimplant 10, and thus the description of the connector 14 also describesthe connector 114 of the implant 110.

The first and the second surfaces 116 and 120 are illustrated as planar,but can be curved. The first surface 116 defines an aperture 124 atgenerally an axial center thereof. Aligned with the aperture 124 is acounterbore 126, which is defined within the base 112. The aperture 124and the counterbore 126 are aligned along a longitudinal axis B of thestem 118 (FIG. 9). Extending from the second surface 120 are a pluralityof anti-rotational pins 128.

The stem 118 extends from the second surface 120 of the base 112. Thestem 118 generally includes a base end 130 at the second surface 120 ofthe base 112 and a tip end 132 that is opposite to the base end 130. Thebase end 130 can be integral with the base 112 or secured thereto in anysuitable manner, such as with a weld. The stem 118 defines a bore 134that is aligned with the aperture 124 and the counterbore 126 along thelongitudinal axis B. The bore 134 extends from the counterbore 126 tothe tip end 132.

At the tip end 132 the stem 118 includes a solid portion 136. The solidportion 136 includes a pair of recesses 138 at the tip end 132. Betweenthe solid portion 136 and the base 112 is a mesh portion 140, whichdefines a plurality of openings 142. The mesh portion 140 and theopenings 142 are substantially similar to the mesh portion 44 and theopenings 54 respectively of the implant 10. Thus, the above descriptionof the mesh portion 44 and the openings 54 also describes the meshportion 140 and the openings 142 respectively.

The bore 134 of the stem 118 is sized to house a plurality of washers144. Each washer 144 generally defines a cone shape with an open tip146. The washers 144 are arranged in multiple washer pairs, 148 a-148 ffor example, such that the open tips 146 oppose one another. The washers144 are configured to be compressible to apply a spring force that holdsthe implant in bone, as well as to potentially absorb forces applied tothe base and act as dampers. The washers 144 are aligned in the bore 134such that the open tips 146 are aligned along the longitudinal axis B(FIG. 9). In place of the washers 144 can be any suitable resilientcomponent or compliant material.

The washers 144 are retained within the stem 118 with an end cap 150.The end cap 150 is generally annular and defines a receptacle 152including cap threads 154. A proximal surface 156 of the end cap 150includes tabs 158, which are sized to cooperate with the recesses 138 ofthe solid portion 136.

To retain the end cap 150 against the tip end 132 of the stem 118, afastener 160 is used. The fastener 160 generally includes a head 162, ashaft 164 with a distal end 166, and fastener threads 168 at the distalend 166. The fastener 160 is inserted into the bore 134 such that thehead 162 is seated in the counterbore 126 and abuts the nearest washerpair 148 a. The shaft 164 extends through the open tips 146 of each ofthe washers 144, and into the receptacle 152 such that a few fastenerthreads 168 nearest the distal end 166 initially engage a few of the capthreads 154 nearest the proximal surface 156.

With reference to FIG. 10, to compress the mesh portion 140, therebycausing it to expand outward from the longitudinal axis B, the fastener160 is rotated using any suitable device, such as the driver 80illustrated in FIG. 4. Rotation of the fastener 160 causes the fastenerthreads 168 to engage additional cap threads 154 and extend through thereceptacle 152 so that the fastener 160 extends through the end cap 150.Engagement between the head 162 of the fastener 160 and the counterbore126 prevents the fastener 160 from moving along the longitudinal axis B,which results in the end cap 150 being pulled toward the base 112. Asthe end cap 150 is pulled toward the base 112, the mesh portion 140 iscompressed between the end cap 150 and the base 112 along thelongitudinal axis B.

With additional reference to FIG. 11, the implant 110 can be compressedwith the compression tool 90 rather than the fastener 160. Thecompression tool 90 is initially positioned such that the flange 99 isseated in the counterbore 126 and the tool threads 98 only partiallyengage the cap threads 154. As the compression tool 90 is rotated, thetool threads 98 cooperate with and engage additional threads 154 of theend cap 150 to pull the end cap 150 toward the base 112. The meshportion 140 is compressed between the end cap 150 and the base 112, thuscausing the mesh portion 140 to expand outward from the longitudinalaxis B. The compression tool 90 is rotated in an opposite direction todisengage the implant 110. The mesh portion 140 remains compressed afterthe compression tool 90 is removed due to cooperation with surroundingbone and properties of material included in the mesh portion 140.

With additional reference to FIG. 12, the implant 110 including thefastener 160 is implanted in the femur 102. The implant 110 is implantedin the femur 102 in substantially the same manner as the implant 10.Therefore, the above description of implantation of the implant 10 alsoapplies to the implant 110. While the implant 110 is illustrated as afemoral implant, the mesh portion 140 can be included in an anchoringstem of any other suitable type of implant to facilitate fixation of theimplant in bone or tissue.

With reference to FIG. 13, another implant according to the presentteachings is illustrated at reference numeral 210. The implant 210includes various components that are substantially similar to componentsof the implant 110, and thus are illustrated with like referencenumbers. For example, the implant 210 similarly includes the base 112,the connector 114, the anchor or stem 118, the washers 144 arranged inmultiple washer pairs 148 a-f in the stem, the aperture 124, thecounterbore 126, and the bore 134.

The fastener 160 is positioned such that the head 162 is seated in thecounterbore 126, the shaft 164 extends through the bore 134, and thedistal end 166 extends beyond the tip end 132. The fastener 160 includesa flange 170 that abuts a shoulder 172 at a distal end of thecounterbore 126 to prevent the fastener 160 from passing through thecounterbore 126 and the base 112. To prevent the washers 144 fromexiting the bore 134 at the tip end 132, a retention clip 174 is seatedwithin the bore 134 distal to the most distal washer 144. The retentionclip 174 can be secured within the bore 134 in any suitable manner. Forexample, the retention clip 174 can be seated within an annular recessdefined within the bore 134.

Unlike the implant 110, the stem 118 of the implant 210 is solid anddoes not include the mesh portion 140. The stem 118 of the implant 210can, however, include a mesh portion substantially similar to the meshportion 140 as well.

The implant 210 further includes an expandable anchor cap 220. Theanchor cap 220 generally includes an anchor head portion 222 and ananchor body portion 224. The anchor cap 220 defines a bore 226 thatextends through the anchor head portion 222 and the anchor body portion224. The bore 226 is aligned with a longitudinal axis C (FIG. 14) of thestem 118.

The head portion 222 generally includes a support sphere 228, which isconnected to the anchor body portion 224 with a neck 230. At an end ofthe support sphere 228 opposite to the neck 230 is a boss 232. Theanchor body portion 224 includes a solid base 234, a mesh portion 236,and a tip 238. Extending from the solid base 234 toward the neck 230 aretabs 240, which are sized and shaped to mate with the recesses 138 ofthe stem 118. The mesh portion 236 is similar to the mesh portion 44 ofthe implant 10 and the mesh portion 140 of the implant 110, and thusdefines openings 242 that extend through the mesh portion 236 to thebore 226. The descriptions of the mesh portions 44 and 140 also describethe mesh portion 236. The tip 238 defines a concave outer shape andincludes anchor threads 244 in the bore 226.

As illustrated in FIG. 14 for example, the anchor cap 220 is mountedspaced apart from the tip end 132 of the stem 118 with the fastener 160,or any other suitable fastening device. The fastener 160 is positionedsuch that the head 162 is seated in the counterbore 126 and the shaft164 extends through the stem 118 and into the anchor cap 220. FIG. 15 isa cross-sectional view showing the fastener 160 extending through themesh portion 236 of the anchor cap 220. The fastener threads 168 at thedistal end 166 of the fastener 160 partially engage the anchor threads244 of the anchor cap 220 at the tip portion 238 in the uncompressedposition of FIG. 14.

With additional reference to FIG. 16, the mesh portion 236 of the anchorcap 220 is compressed by rotating the fastener 160 in any suitablemanner, such as by using the driver 80 of FIG. 4. Rotation of thefastener 160 causes the fastener threads 168 to engage additional anchorthreads 244 of the anchor cap 220 and draw the tip 238 toward the solidbase 234, thereby compressing the mesh portion 236 therebetween andcausing the mesh portion 236 to expand outward from the longitudinalaxis C. The mesh portion 236 can be compressed before or after theanchor cap 220 is coupled to the anchor or stem 118, as furtherdescribed herein.

With additional reference to FIG. 17, the mesh portion 236 of the anchorcap 220 can also be compressed with the compression tool 90. Thecompression tool 90 is orientated such that flange 99 is seated in thecounterbore 126 and the shaft 94 extends through the stem 118 to engagethe anchor cap 220. The shaft 94 extends through the anchor cap 220 suchthat the tool threads 98 cooperate with the anchor threads 244 at thetip 238 of the anchor cap 220. Rotation of the tool 90 causes the toolthreads 98 to engage additional anchor threads 244 thereby pulling theanchor tip 238 toward the solid base 234 of the anchor cap 220 andcompressing the mesh portion 236 therebetween. The compression tool 90is rotated in an opposite direction to disengage the anchor cap 220. Themesh portion 236 remains compressed after the compression tool 90 isremoved due to cooperation with surrounding bone and properties ofmaterial included in the mesh portion 236.

The implant 210 can be implanted in substantially the same manner as theimplants 10 and 110. Thus the description of the implantation of theimplants 10 and 110 also describes implantation of the implant 210.Unlike the implants 10 and 110, the anchor cap 220 includes theexpandable mesh portion 236. Thus, once the implant 210 is seated in thefemur 102, the fastener 160 is rotated to compress the mesh portion 236thereby causing the mesh portion 236 to extend out from the longitudinalaxis C and engage the surrounding bone of the femur 102 to secure theimplant 210 to the femur 102. While the implant 210 is illustrated as afemoral implant, the anchor cap 220 including the compressible andexpandable mesh portion 236 can be included in any other suitable typeof implant to facilitate fixation of the implant in bone or tissue.

FIGS. 18A-18C illustrate an additional method for implanting the implant210. With initial reference to FIG. 18A, the anchor cap 220 is initiallyimplanted within any suitable bone hole in any suitable manner. Forexample, the anchor cap 220 can be implanted within a bone hole formedat the neck 104 of the femur 102. With additional reference to FIG. 18B,the mesh portion 236 is compressed such that it extends outward and intothe bone hole to anchor the anchor cap 220 within the femur 102. Themesh portion 236 can be compressed in any suitable manner, such as witha tool that engages the anchor threads 244 and draws the tip 238 and thesolid base 234 together.

As illustrated in FIG. 18C, the implanted anchor cap 220 serves as ananchor for the remainder of the implant 210. The stem 118 is insertedwithin the bone hole and the fastener 160 is threaded into engagementwith the anchor threads 244. A gap is defined between the tip end 132 ofthe stem 118 and the solid base 234 of the anchor cap 220. The base 112of the implant 110 is seated against the anterior surface 106 of thefemur 102, and the pins 128 extending from the base 112 engage theanterior surface 106. As the fastener 160 is tightened, the fastenerthreads 168 of the fastener 160 thread further into the anchor threads244 thereby drawing the remainder of the implant 210 toward the anchorcap 220, which compresses the base 112 against the femur 102, therebyfacilitating healing and strengthening the femur bone 102.

An additional implant according to the present teachings is illustratedin FIGS. 19 and 20 at reference numeral 310. The implant 310 generallyincludes an anchor or sleeve 312 and a cap 314. The sleeve 312 generallyincludes a first end 316, a second end 318 that is opposite to the firstend 316, and a sidewall 320 that extends between the first end 316 andthe second end 318. The sidewall 320 is generally cylindrical, asillustrated in FIG. 20 for example. The sleeve 312 defines a bore 322that extends through the sleeve 312 from the first end 316 to the secondend 318. A longitudinal axis D of the sleeve 312 extends through anaxial center of the bore 322.

The sleeve 312 includes a first sleeve portion 324 at the first end 316,a second sleeve portion 326 at the second end 318 and an intermediateportion 328 about half-way between the first end 316 and the second end318. The first sleeve portion 324, the second sleeve portion 326, andthe intermediate portion 328 are generally solid and generally notcompressible. At the second end 318 the second sleeve portion 326defines a recess 329.

Between the intermediate portion 328 and the first sleeve portion 324 isa first mesh portion 330. Between the intermediate portion 328 and thesecond sleeve portion 326 is a second mesh portion 332. Each of thefirst mesh portion 330 and the second mesh portion 332 define aplurality of openings 334. The first mesh portion 330 and the secondmesh portion 332 are substantially similar to the compressible meshportion 44 of the implant 10, the mesh portion 140 of the implant 110,and the mesh portion 236 of the anchor cap 220. Thus, the description ofthe mesh portions 44, 140, and 236 also describe the first and thesecond mesh portions 330 and 332 of the sleeve 312.

The cap 314 includes a first surface 336 and a second surface 338 thatis opposite to the first surface 336. A side surface 340 extends betweenthe first surface 336 and the second surface 338. The side surface 340defines a generally cylindrical outer shape of the cap 314. The cap 314defines a cap bore 342 therein. The cap bore 342 includes internal capthreads 344. A pair of flanges 346 extend from the first surface 336 andare sized and shaped to be received in the recess 329.

With additional reference to FIG. 21, a sleeve compression tool isillustrated at reference numeral 360. The tool 360 generally includes ahandle 362, a shaft 364 that extends from the handle 362 and includes adistal end 366, and tool threads 368 at the distal end 366. Between thedistal end 366 and the handle 362 is a flange 370. The sleevecompression tool 360 is operable to couple the sleeve 312 and the cap314 together and compress the first and the second mesh portions 330 and332, as described herein.

With additional reference to FIG. 22, the implant 310 is illustratedassembled and seated within an intramedullary canal 380 of the femur 102at the isthmus 382 of the intramedullary canal 380. To implant theimplant 310 in the intramedullary canal, the sleeve 312 is mated withthe sleeve compression tool 360 such that flange 370 of the tool 360mates with the first sleeve portion 324, the shaft 364 extends throughthe bore 322 to the second end 318 of the sleeve 312, and the toolthreads 368 at the distal end 366 cooperate with the first few capthreads 344 of the cap 314 that are nearest the flange 346 in order tohold the cap 314 at the second end 318 of the sleeve 312.

As illustrated in FIG. 23 for example, with the implant 310 at theisthmus 382 of the intramedullary canal 380 the sleeve compression tool360 is rotated so that the tool threads 368 engage additional capthreads 344 of the cap 314 and thus draw the cap 314 toward the firstend 316 of the sleeve 312. As the cap 314 is drawn toward the first end316, the sleeve 312 is compressed between the flange 370 and the cap314. More specifically, the first mesh portion 330 and the second meshportion 332 each compress along the longitudinal axis D and expandoutward in a direction generally perpendicular to the longitudinal axisD. As the first mesh portion 330 and the second mesh portion 332 expandoutward from the longitudinal axis D, the sidewall surfaces 320 thereofengage the intramedullary canal 380 to secure the implant 310 inposition. After the first and second mesh portions 330 and 332 arecompressed, the sleeve compression tool 360 is rotated in an oppositedirection and removed. The intermediate portion 328 is solid and doesnot expand or compress, which helps maintain the bore 322 aligned withthe longitudinal axis D and facilitates cooperation between the bore 322and another implant, as described herein. The intermediate portion 328can include a compressible and expandable mesh portion as well.

With additional reference to FIG. 24, the sleeve 312 is illustrated asanchoring a distal femoral implant 410. The distal femoral implant 410is anchored to the sleeve 312 with a spindle 412 and a taper adaptor414. The spindle 412 includes a spindle base 416 with an anchor orspindle stem 418 extending from a first side of the base 416 and aspindle male Morse taper surface connector 420 extending from a secondside of the base 416, which is opposite to the first side. The spindlestem 418 includes spindle threads 422 at a distal end 424 thereof. Thetaper adaptor 414 includes a female Morse taper surface 426 and a maleMorse taper surface 428, which are at opposite ends of the taper adaptor414. The distal femoral implant 410 includes a female Morse tapersurface 430 and an aperture 432 configured to receive a screw fastener434.

To connect the spindle 412 to the sleeve 312, the spindle stem 418 isinserted through the bore 322 and the distal end 424 is threadablyengaged with the cap threads 344 of the cap 314. The spindle 412 isorientated and the spindle stem 418 is provided with an appropriatelength such that the spindle base 416 is at a distal end 103 of thefemur 102 when coupled with the sleeve 312. The taper adaptor 414 isconnected to the spindle 412 through cooperation between the femaleMorse taper surface 426 and the spindle male Morse taper surfaceconnector 420. The distal femoral implant 410 is connected to the taperadaptor 414 through cooperation between the male Morse taper surface 428and the female Morse taper surface 430 of the distal femoral implant410. The fastener 434 can be used to further secure the distal femoralimplant 410 to the taper adaptor 414. In addition to securing the distalfemoral implant 410 to the femur 102, the sleeve 312 can be used tosecure any suitable implant to any suitable bone or tissue.

With additional reference to FIG. 25, a body portion 440 of the taperadaptor 414 can include a mesh portion 442 that defines a plurality ofopenings 444. The mesh portion 442 is substantially similar to the meshportions 44, 140, 236, 330, and 332 described herein, and thus thedescription of these mesh portions also describes the mesh portion 442.In response to a shock force across the assembly of FIG. 25, the meshportion 442 compresses to absorb the shock and act as a damper. The meshportion 442 thus increases patient comfort and reduces stress on theassembly of FIG. 25 to prolong the life of the assembly.

With additional reference to FIG. 26, the implant 10 of FIGS. 1-5 and 7is illustrated with the base 12 including a mesh portion 480 between thefirst surface 18 of the base 12 and the second surface 20 of the base12. The mesh portion 480 defines a plurality of openings 482 in the base12. The mesh portion 480 is substantially similar to the mesh portions44, 140, 236, 330, 332, 442 described herein, and thus the descriptionof these mesh portions also describes the mesh portion 480. The meshportion 480 is compressible to dampen shock forces experienced by theimplant 10. The mesh portion 480 thus reduces stress on the implant 10and the femoral head 34 connected thereto to prolong the life of theimplant 10 and increase patient comfort.

With additional reference to FIG. 27A, another implant according to thepresent teachings is illustrated at reference numeral 510. The implant510 generally defines a cup or hemispherical shape. The implant 510includes a bone engaging surface 512 and an articulation surface 514that is opposite to the bone engaging surface 512. The bone engagingsurface 512 is generally convex in relation to the articulation surface514. The articulation surface 514 is generally concave with respect tothe bone engaging surface 512. The implant 510 is thus generallyconfigured as an acetabular cup.

The articulation surface 514 defines a circular aperture 516 thatprovides an opening to a receptacle 518, which is also defined by thearticulation surface 514. The articulation surface 514 further defines athreaded bore 520 at an axial center thereof. A longitudinal axis Eextends through an axial center of the articulation surface 514, theaperture 516, and the threaded bore 520. Surrounding the aperture 516 isa planar base surface 522.

The implant 510 further includes a generally ring shaped mesh portion530. The mesh portion 530 is proximate to both the planar base surface522 and an equator of the implant 510. The mesh portion 530 definesopenings 532 that extend entirely through the mesh portion 530. The meshportion 530 is substantially similar to the mesh portions 44, 140, 236,330, 332, 442, 480 described herein, and thus the description of thesemesh portions also describes the mesh portion 530. As illustrated inFIG. 27B, the mesh portion 530 can be compressed along the longitudinalaxis E. Such compression also causes expansion of the mesh portion 530away from the longitudinal axis E in a direction that is generallyperpendicular to the longitudinal axis E.

With additional reference to FIG. 28, the mesh portion 530 can becompressed using a suitable compression tool, such as the cup compressor550. The cup compressor 550 generally includes a threaded tip 552, whichextends from a flange 554. The flange 554 is connected to a handle 556with a connector 558. To compress the mesh portion 530, the threaded tip552 is inserted within the threaded bore 520 to bring the flange intocontact with the planar base surface 522. The handle 556 is rotated sothat the threaded tip 552 progressively threads into the threaded bore520 and the flange 554 applies force to the planar base surface 522,thereby compressing the mesh portion 530. The handle 556 is rotated inan opposite direction to disengage the implant 510. The mesh portion 530remains compressed after the cup compressor 550 is removed due tocooperation with surrounding bone and properties of material included inthe mesh portion 530.

With additional reference to FIG. 29, the implant 510 can be implantedinto an acetabulum 580 of a pelvis 582, for example. The acetabulum 580can be prepared in any suitable manner, such as by milling or reaming.To affix the implant 510 at the acetabulum 580, the implant 510 is matedwith the cup compressor 550 as described above and then seated withinthe prepared acetabulum 580. Rotation of the handle 556 causes thethreaded tip 552 to thread deeper within the threaded bore 520 andcompress the flange 554 against the planar base surface 522, which thuscompresses the mesh portion 530 along the longitudinal axis E. The meshportion 530 also expands outward from the longitudinal axis E to engagethe surrounding acetabulum 580 and secure the implant 510 therein.Securing the implant 510 with the mesh portion 530 can make anchor pinsand screws unnecessary.

With additional reference to FIG. 30A, another implant according to thepresent teachings is illustrated at reference numeral 510′. The implant510′ is similar to the implant 510, and thus like features aredesignated with the same reference numbers, but include the prime (′)symbol. The implant 510′ further includes a flared or conical lipportion 534 of the bone engaging surface 512′. The flared portion 534abuts the mesh portion 530′, extends around the bone engaging surface512′ proximate to the equator of the implant 510′, and extends outwardfrom the longitudinal axis E. The mesh portion 530′ extends along thelongitudinal axis E from the flared portion 534. The flared portion 534provides an enlarged base for the mesh portion 530′, and thus the meshportion 530′ can have a larger outer diameter than the mesh portion 530,thereby allowing the mesh portion 530′ to extend further intosurrounding bone, for example, to enhance fixation of the implant 510′at an implant site. The implantation of the implant 510 described abovealso applies to the implant 510′.

FIG. 30B illustrates another implant according to the present teachingsat reference numeral 510″. The implant 510″ is similar to the implant510, and thus like features are designated with the same referencenumbers, but include the double prime (″) symbol. Unlike the implant510, the mesh portion 530″ and the planar base surface 522″ attachedthereto of the implant 510″ are modular with respect to the remainder ofthe implant 510″. The implant 510″ includes a flange 536 and defines aseat 538 for the modular mesh portion 530″. The mesh portion 530″ ispositioned over the flange 536 and positioned on the seat 538. Uponcompression of the mesh portion 530″, the mesh portion 530″ expands intosurrounding bone and retains the implant 510″ at an implant site. Theimplant 510″ can be compressed and implanted in a manner similar to thatdescribed above with respect to the implant 510, with the cup compressor550 modified to accommodate the rigid flange 536.

With additional reference to FIGS. 31-35, another implant according tothe present teachings is illustrated at reference numeral 610. Theimplant 610 generally includes a cup component 612 and a retentioncomponent 614. The cup component 612 generally defines a hemisphericalshape. The cup component 612 includes a bone engaging surface 616 and anarticulation surface 618 that is opposite to the bone engaging surface616. The bone engaging surface 616 is generally convex in relation tothe articulation surface 618. The articulation surface 618 is generallyconcave with respect to the bone engaging surface 616. The implant 610is thus generally configured as an acetabular cup.

The articulation surface 618 defines a circular aperture 620 thatprovides an opening to a receptacle 622, which is also defined by thearticulation surface 618. The articulation surface 618 further defines athreaded bore 624 at an axial center thereof. A longitudinal axis Fextends through an axial center of the articulation surface 618 and thethreaded bore 624. Surrounding the receptacle 622 is a planar basesurface 625. At an exterior equator 626 of the cup component are aplurality of biasing surfaces 628, which are spaced apart about theequator. The biasing surfaces 628 are curved away from the longitudinalaxis F.

The retention component 614 generally includes a retention ring 640 witha plurality of retention barbs 642. The retention barbs 642 protrudefrom an undersurface 644 of the retention ring 640 and are spaced apartabout the retention ring 640. The retention barbs 642 include a pointeddistal end 646 and a barb body 648 between the undersurface 644 of theretention ring 640 and the pointed distal end 646.

With reference to FIG. 33 for example, the barb body 648 includes anouter surface 650 and an inner surface 652. The outer surface 650includes a plurality of outer notches 654 therein. The inner surface 652includes a plurality of inner notches 656 therein. The outer notches 654are larger than the inner notches 656 to facilitate bending of theretention barbs 642 away from the longitudinal axis F, as illustrated inFIG. 34. The retention component 614, including the retention barbs 642,can be made of any suitable type of material, such as a suitablemetallic, fibrous, or polymeric component.

To assemble the implant 610, the retention barbs 642 are aligned withthe biasing surfaces 628 and the retention component 614 is forced ontothe cup component 612 with, for example, the cup compressor 550. Inparticular, the threaded tip 552 of the cup compressor 550 is connectedto the threaded bore 624. As the threaded tip 552 is threaded deeperinto the threaded bore 624, the flange 554 presses the retention ring640 against the cup component 612 such that the undersurface 644 of theretention component 614 contacts the planar base surface 625 of the cupcomponent 612 and the retention barbs 642 are forced into contact withthe biasing surfaces 628, as illustrated in FIGS. 32 and 33 for example.Because the biasing surfaces 628 are curved outward from thelongitudinal axis F, the retention barbs 642 are forced outward from thelongitudinal axis F into an extended position, as illustrated in FIG. 34for example. Movement of the retention barbs 642 to the extendedposition of FIG. 34 is facilitated by the outer notches 654 being largerthan the inner notches 656, which results in less resistance to bendingof the retention barbs 642 at the outer surface 650 thereof.

In the extended position of FIG. 34, the pointed distal ends 646 of eachretention barb 642 extend into surrounding bone to secure the implant610 at a desired implant site. For example and with reference to FIG.35, the implant 610 can be implanted at an acetabulum 580 of a pelvis582. After the acetabulum 580 is prepared, such as by reaming forexample, the cup component 612 is seated in the acetabulum and theretention component 614 is compressed onto the cup component 612 using,for example, the cup compressor 550. Compression of the retentioncomponent 614 onto the cup component 612 causes the retention barbs 642to extend into the surrounding bone, as described above, to secure theimplant 610 at the acetabulum 580 without the need for bone cement.

With additional reference to FIGS. 36 and 37, another implant accordingto the present teachings is illustrated at reference numeral 710. Theimplant 710 generally includes a cup component 712 and a retentioncomponent 714. The cup component 712 generally defines a hemisphericalshape. The cup component 712 includes a bone engaging surface 716 and anarticulation surface 718 that is opposite to the bone engaging surface716. The bone engaging surface 716 is generally convex in relation tothe articulation surface 718. The articulation surface 718 is generallyconcave with respect to the bone engaging surface 716. The implant 710is thus generally configured as an acetabular cup.

The retention component 714 includes a plurality of retention fins 720that extend outward from and extend around an outer perimeter wall 722of the implant 710. The retention fins 720 can be made of any suitablematerial, including the material of the implant 710. For example, thefins 720 can be formed as a porous metal construct added to the boneengaging surface 716 through additive manufacturing. The porous metalconstruct can be similar to the Regenerex® porous metal construct soldby Biomet, Inc. and the additive manufacturing process can be similar tothe electron beam melting process sold by Arcam, AB.

The retention fins 720 are generally flexible. The fins 720 can flexbetween an extended position, in which the fins 720 extend to a greatestextent outward from the outer wall of the implant 710, and a bent orengaged position, in which the fins 720 do not extend the greatestextent outward from the outer wall. In the extended position, which isillustrated in FIG. 37, the retention fins 720 are configured to engagebone to retain the implant 710 at an implantation site. Duringimplantation, the implant 710 is impacted into bone. As the implant 710is impacted, the retention fins 720 flex or bend inward to the bent orengaging position. The fins 720, however are biased and subsequentlyextend outward to engage surrounding bone after implantation to securethe implant 710 to the bone.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosure. Individual elements or featuresof a particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the disclosure, and all such modificationsare intended to be included within the scope of the disclosure.

What is claimed is:
 1. An acetabular cup implant comprising: a curvedouter surface; a concave surface opposite to the curved outer surface,an axis of the acetabular cup implant extends through an axial center ofthe concave surface; and a retention component configured to compressalong the axis and expand from the axis to engage surrounding bone ortissue at an implantation site to secure the implant at the implantationsite.
 2. The acetabular cup implant of claim 1, wherein the retentioncomponent includes a plurality of flexible fins that are configured tofirst compress during implantation into the implantation site and thenexpand into the surrounding bone at the implantation site.
 3. Theacetabular cup implant of claim 1, wherein a threaded bore is definedthrough the concave surface; wherein the threaded bore is configured tocooperate with a threaded tip of a compressor device including a flange;and wherein rotation of the threaded tip when the threaded tip is incooperation with the threaded bore and the flange contacts an implantsurface between the bone engaging outer surface and the concave surface,compresses the acetabular cup implant along the axis, compresses theretention component along the axis, and expands the retention componentradially outward from the axis.
 4. The acetabular cup implant of claim3, wherein the acetabular cup implant includes at least one of a flaredsurface or a conical surface at the equator of the acetabular cupimplant.
 5. The acetabular cup implant of claim 1, wherein the concavesurface is configured to cooperate with a femoral implant to replace ahip joint.
 6. The acetabular cup implant of claim 1, wherein theretention component includes a compressible and expandable mesh alignedalong the axis and defining a plurality of openings, the mesh isconfigured to compress along the axis and expand from the axis to engagesurrounding tissue at the implantation site to secure the acetabular cupimplant at the implantation site.
 7. The acetabular cup implant of claim6, wherein the mesh is included in an anchor and arranged between afirst solid anchor portion and a second solid anchor portion.
 8. Theacetabular cup implant of claim 1, wherein the retention component isconfigured substantially at a rim of the acetabular cup implant.
 9. Anacetabular cup implant comprising: a curved bone engaging outer surface;a concave surface opposite to the bone engaging surface, an axis of theacetabular cup implant extending through an axial center of the concavesurface; and a retention component including a retention ring, whereinupon compression, the retention component is forced outward from theaxis to engage surrounding bone or tissue at an implantation site tosecure the acetabular cup implant at the implantation site.
 10. Theacetabular cup implant of claim 9, further comprising a threaded bore atthe axis.
 11. The acetabular cup implant of claim 10, wherein thethreaded bore is configured to cooperate with a threaded tip of acompressor device including a flange; and wherein rotation of thethreaded tip when the threaded tip is in cooperation with the threadedbore compresses the retention ring against the cup component.
 12. Theacetabular cup implant of claim 9, further comprising a plurality ofconcave biasing surfaces spaced apart about an equator of the curvedbone engaging surface; wherein the retention component includes aplurality of retention barbs extending from the retention ring andspaced apart about the retention ring; and wherein upon compression ofthe retention component, the retention barbs contact the biasingsurfaces and the retention barbs are forced outward from the axis toengage surrounding bone or tissue at an implantation site to secure theacetabular cup implant at the implantation site.
 13. The acetabular cupimplant of claim 12, wherein the biasing surfaces and the retentionbarbs are spaced apart at similar intervals.
 14. The acetabular cupimplant of claim 12, wherein each barb includes an outer surface and aninner surface that is opposite to the outer surface; and wherein theouter surface defines at least one first notch therein and the innersurface defines at least one second notch therein, the first notch islarger than the second notch.
 15. The acetabular cup implant of claim 9,wherein the retention component includes a compressible and expandablemesh aligned along the axis and defining a plurality of openings, themesh configured to compress along the axis and expand from the axis toengage surrounding tissue at the implantation site to secure theacetabular cup implant at the implantation site.
 16. An acetabular cupimplant comprising: an outer surface; a concave surface opposite to theouter surface; a centerline axis extending through an axial center ofthe concave surface; and a retention component configured to compressalong the centerline axis and expand from the centerline axis to engagesurrounding bone or tissue at an implantation site to secure theacetabular cup implant at the implantation site.
 17. The acetabular cupimplant of claim 16, further comprising: a threaded bore defined throughthe concave surface; wherein the threaded bore is configured tocooperate with a threaded tip of a compressor device including a flange;and wherein rotation of the threaded tip when the threaded tip is incooperation with the threaded bore and the flange is in contact with animplant surface between the bone engaging outer surface and the concavesurface, compresses the acetabular cup implant along the centerlineaxis, compresses the retention component along the centerline axis, andexpands the retention component radially outward from the centerlineaxis.
 18. The acetabular cup implant of claim 16, wherein the acetabularcup implant includes at least one of a flared surface or a conicalsurface at an equator of the implant.
 19. The acetabular cup implant ofclaim 16, wherein the retention component includes a compressible andexpandable mesh aligned along the centerline axis and defining aplurality of openings, the mesh configured to compress along thecenterline axis and expand from the centerline axis to engagesurrounding tissue at the implantation site to secure the acetabular cupimplant at the implantation site.
 20. The acetabular cup implant ofclaim 16, further comprising a plurality of concave biasing surfacesspaced apart about an equator of the outer surface; wherein theretention component includes a plurality of retention barbs extendingfrom and spaced apart about the retention component; and wherein uponcompression of the retention component, the retention barbs contact thebiasing surfaces and the retention barbs are forced outward from theaxis to engage surrounding bone or tissue at an implantation site tosecure the acetabular cup implant at the implantation site.